Electro-mechanical actuator with permanent magnet



April 26, 1966 E. J. YOUNG 3,248,499

ELECTRO-MECHANICAL ACTUATOR WITH PERMANENT MAGNET Filed Sept. l5, 1962 5Sheets-Sheet 2 April 26, 1966 E. J. YOUNG 3,248,499

ELECTRO-MECHANICAL ACTUATOR WITH PERMANENT MAGNET Filed Sept. 13, 1962 3Sheets-Sheet 5 Ff. y 132 156 "42 lf2 .X24 15.5

United States Patent O 3 248,499 ELECTRO-MECHACAL ACTUATR WITH PERMANENTMAGNET Edward l. Young, Hawthorne, Calif., assignor to Digital AnalogTechnical Associates, Inc., El Segundo, Calif.,

a corporation of Caiifornia Filed Sept. 13, 1962, Ser. No. 223,331 17Ciaims. (Cl. 20d- 93) This invention relates to an actuator employingmagnetic force and, more particularly, pertains to such a device whichemploys a movable armature for an actuator and incorporates permanentmagnet means for releasably maintaining the armature at one of its twoalternate positions. Such an actuator may be used for various purposesincluding the remote operation of valves but has special usefulness inswitch mechanisms.

Gne of the appli-cations of the invention wherein it has special utilityis an electromagnet binary relay capable of :operation at much higherspeeds than conventional relays. The invention is also applicable to theconstruction of a monostable relay. In addition, certain principles ofthe invention may be embodied in a push button switch, which switch may,if desired, be adapted for remote actuation as well as manual actuation.

With reference to the embodiment of the invention as an electromagneticbinary relay, it is well known that an electromagnetic relay with amovable armature, as distinguished from a purely electronic relay withno moving parts, is desirable for many uses because such a relay may beof rugged construction and may operate in a positive manner withsubstantial actuation force. Conventional electromagnetic relays,however, are bulky, relatively expensive and inherently slow inoperation. While no mechanical electromagnetic relay with a movablearmature can operate in microseconds to compete in speed with purelyelectronic relays, nevertheless, there is a definite need for anelectromagnetic relay such as a binary relay, that can operate inmicroseconds. The present invention meets this demand with a highlyreliable binary relay that is of miniature size, of simple inexpensiveconstruction, immune to shock and vibration, and is capable of operationat a rate of 2,00() or more times per second.

Generally described, the binary relay of the invention has aferromagnetic structure including permanent magnet means and two spacedconfronting pole pieces with an armature movably mounted in the gapbetween the confronting pole pieces. The permanent magnet means createsa normal magnetic field in the ferromagnetic structure with concentratediiux across the gap and through the armature to cause the armature toadhere magnetically to whichever pole piece it may abut. The use of anarmature of small mass in a high concentration of magnetic flux causesthe armature to be latched at its two opposite stable positions with alatching force capable of withstanding exceedingly high shock forcesalong its operating axis.

Associated with the ferromagnetic structure is an electromagnetic coilmeans capable of overcoming the normal magnetic field created by thepermanent magnet means. Remotely controlled means energizes theelectromagnetic coil means reversibly to shift the armature reversiblyacross the gap between the two pole pieces.

Preferably, a concentric arrangement is used with the two pole piecesand the intervening armature aligned along an axis and surrounded by twosubstantially coextensive annular means, one annular means being thepermanent magnet means and the other annular means being theelectromagnetic coil means. The permanent magnet means must beoutermost.

"ice

In the preferred practice of the invention the fer-romagnetic structureincludes two aligned oppositely polarized cylindrical permanent magnetswhich may be termed right hand and left hand magnets and twocorresponding left hand and right hand coils inside the cylindricalmagnets with two corresponding right hand and left hand axial polepieces inside the two coils respectively. The two cylindrical permanentmagnets create two opposite toroidal magnetic fields with concentratedflux in the region of the armature and the two coils act as `one coiland are reversible to create a reversible controlling magnetic field.Current iiow in one direction through the two coils weakens or nullitiesthe field of the right hand magnet and simultaneously reinforces thefield of the lefthand magnet to cause the armature to shift with a snapaction from the right pole piece to the left pole piece. In like mannerreverse current iiow weakens or nullifies the iield of the left handmagnet and augments the lield of the right hand magnet to shift thearmature from its left hand position to its right hand position.

In a second embodiment of the binary relay, at least one cylindricalpermanent magnet is provided to create a single toroidal magnetic fieldthrough the two confronting axial pole pieces to latch the armature atits two positlons. Two opposed annular coils are provided to create two`opposite control fields, the coil current iiow being reversible toreverse the two bucking control fields for shifting lthe karmatureselectively in its two opposite directions.

As will be explained, a feature of the invention is the employment ofresilient switch arm means that is stressed in iiexure for creatingdesirable contact pressure. Preferably associated inclined cam surfacesare provided for urging and holding the switch arm means against thcooperating contact means.

With reference to the utility of the invention in the construction ofpush button switches, one such switch described hereinafter employs apermanent magnet to maintain a movable switch member in a normalposition and the switch member is shifted to its alternate position by amanually operable push button. In the selected embodiment of theinvention, electromagnetic vmeans under remote control may also beavailable to shift the switch member to its alternate position.

In a second embodiment of a push button switch, two permanent magnetsreleasably latch a switch member at whichever of its two alternatepositions it may be placed. 'Two switch buttons are adapted to shift theswitch member mechanically to its two alternate positions respectivelyand, in addition, remotely controlled elec-r tromagnetic means may beprovi-ded to shift the switch member to its two alternate positionsrespectively.

The features and advantages of the invention may be understood from thefollowing detailed description and the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

FIG. l is a longitudinal sectional view of the presently preferredembodiment of the invention with the switch structure omitted forclarity;

FIG. 2 is an exploded view of the functional parts shown in FIG. l;

FIG. 2a is a diagrammatic View showing the configuration of the magneticfields created in the operation of the binary relay;

FIG. 3 is a side elevation of the binary relay on a reduced scale withthe sealed housing or casing for the relay shown in phantom;

FIG. 4 is an end elevation of the binary relay on a somewhat enlargedscale asseen along the line 4--4 of FIG. 3 showing the switch structure;

FIG. 5 is a greatly enlarged View, partly in section and partly in sideelevation, of the structure of the stationary contacts of the doublepole switch, the section being taken along the angular line 5-5 of FIG.4;

FIG. 5a is a fragmentary sectional view showing how two opposite camsurfaces cooperate with a spring wire switch arm;

FIG. 6 is a simplified sectional view of a second embodiment of theinvention; A

FIG. 6a is a diagram showing the configuration of the magnetic fieldsthat are involved in the operation of the second embodiment of theinvention;

FIG. 7 is a simplified sectional View of a third embodiment of theinvention in the form of a relay;

FIG. 8 is a longitudinal sectional view showing how the principles ofthe invention may be embodied in a push button switch which is adaptedfor operation also by remote control; and

FIG. 9 is a view partly in side elevation and partly in section showinghow the principles of the invention may be embodied in a double actingpush button switch which is adapted for operation also by remotecontrol.

The first embodiment of the invention comprises a cylindrical functionalassembly which is mounted in a sealed casing. As indicated in FIGS. 1and 3, the cylindrical functional assembly includes: a central axialtube 10 of a suitable smooth plastic such as Teflon or other nonmagneticmaterial; a spaced pair of coaxial coils comprising a left hand coil 12and a right hand coil 13 surrounding the tube 10; a centralferromagnetic disk 14 with a central aperture 15 to receive the tube 10;a pair of cylindrical permanent magnets abutting the opposite faces ofthe disk 14 comprising a left hand magnet 16 and a right hand magnet 18;a left hand pole piece 20 having an axial extension 22 in the tube 10;aright hand pole piece 24 in the form of a disk having an axialextension 25 in the tube 10, the two axial extensions of the two polepieces being spaced apart to form a gap or working space between the twopole pieces; an actuating armature 26 slidingly mounted in the gapbetween the two pole pieces; and an operating member 28 in the form of apush-pull rod which extends through an axial bore or passageway 30 inthe right hand pole piece 24. The operating member 28may comprise apiece of piano wire having a high resistance to magnetic fiux.

It is apparent that the central disk 14, the two cylindrical magnets 16and 18, and the two pole pieces 20 and 24 form a compact cylindricalferromagnetic structure for creating a high concentration of magneticfiux in the region of the armature 26. The normal magnetic patterncreated by the two magnets comprises two opposite toroidal fields and itis apparent that the central disk 14 has the important function ofconcentrating the flux of both fields in the region of the armature 26.

In this particular embodiment of the invention the armature 26 actingthrough the operating member 28 actuates a double-pole, double-throwswitch. For this purpose two spaced switch arms 32 and 34 in the form ofreresilient wires (FIGS. 1 and 4) are actuated by an operating head 35on the outer end of the operating member 28, each of the two switch armscooperating with two spaced fixed switch contacts 36 and 38 which areshown in FIG. 5. In the construction shown the components of the doublepole switch are mounted on four screws 40 which extend longitudinallyoutward from the right hand pole piece 24.

The described parts of the ferromagnetic structure fit together metal tometal in a compact assembly which in the course of the assemblyprocedure is confined inside a sleeve 42 made of nonmagnetic materialwhich may be aluminum. One end of the aluminum sleeve 42 is swaged toform an inner circumferential bead 44 in engagement with one end of theferromagnetic structure and a second similar swaged bead 45 engages theother end of the ferromagnetic structure. As may be seen in FIG. l, aportion of the aluminum sleeve 42 extends beyond the inner bead 45 toenclose the double pole switch, this end portion of the aluminumsleevebeing provided with two opposite windows or apertures 46. The two endsof the sleeve 42 are closed by aluminum headers 48 which may be brazedthereto, one header having electrical terminals 50 mounted therein in asealed manner for connection to the two coils, the other header havingadditional electrical terminals for the switch contacts. A cylindricalhousing 52 made of non-magnetic metal such as aluminum completelyencloses both the sleeve 42 and the two headers 48 and is brazed orotherwise bonded at itsv ends to the two headers.

As indicated in FIGS. 3 and 4 the two resilient wires 32 and 34 whichform the two switch arms of the switch are rigidly mounted at theirfixed ends between two blocks 62 of insulating material. The two blocks62 are mounted on the outer surface of the right hand pole piece 24 bytwo of the four screws 46, the two blocks being clamped together bymeans of nuts 66 on the screws. As shown in FIG. 1, the operating head35 is of circular construction with a circumferential groove of V-shapedconfiguration that provides two opposite conical cam surfaces 65 and 66for acting on the two wire'switch arms 32 and 34.

The two pairs of fixed contacts 36 and 38 to cooperate with the two wireswitch arms 32 and 34 respectively, are mounted on the remaining twoscrews 40 in the manner shown in FIGS. 4 and 5. Each of the two screwsis surrounded by'a thin insulating sleeve 71. An inner block 68 ofinsulating material and a similar outer block '70 are mounted on the twosleeves 71 with two Contact assemblies sandwiched between the two blockson each of the two sleeves. Each of the two contact assemblies comprisesa fiat wiring terminal 72, a previously mentioned contact 38, aninsulating washer 74, a previously mentioned contact 36 and a secondfiat wiring terminal 75, all of which have apertures or bores that areoversized to permit lateral adjustment of the parts of the assembly inthe screw. When the two contact assemblies are properly adjusted, nuts64 are tightened on the two screws to clamp the parts in a rigid manner.

It is apparent that thetwo contact assemblies comprising the twocontacts 36, the two contacts 38 and the two intervening insulatingwashers 74 constitute. two guide structures for the two resilient wireswitch arms 32 and 34. These two guide structures, which include thefixed contacts, straddle the two resilient wire switch arms and the twoswitch arms, in turn, straddle the operating head 35. The two guidestructures are adjusted eccentrically of the corresponding screws 46 tocrowd and flex the two switch arms against the operating head.

As shown in FIG. 5, the inner insulating block 68 is formed with anoutwardly extending tapered boss 76 that provides a conical cam surfaceor guide surface 78 adjacent the two inner fixed contacts 38 and in likemanner extending tapered boss 80 that provides a conical cam surface orguide surface 82 adjacent the two outer fixed contacts 36.

The manner in which the described invention serves its purpose may bereadily understood from the foregoing description. Normally the twocoils 12 and 13 are deenergized and the normal iiux pattern created bythe two permanent magnets 16 and 18 consists of two opposite toroidalmagnetic fields. FIG. 2a shows two sets of circular arrows 84representing the left hand toroidal magnetic field created by the lefthand magnet 16 and shows two sets of arrows 85 representing the righthand toroidal magnetic field created by the right hand permanent magnet18.

When the two coils 12 and 13 are energized to shift the armature 26 fromits right hand position shown in FIG. 1 to its alternate left handposition, the current fiow which is in the same direction through thetwo coils creates a single overall toroidal control field indicated bythe arrows 86 in FIG. 2a. It is apparent that the control fieldindicated by the arrows 86 is opposed to the 'right hand normal field 85to weaken if not completely cancel the attraction force between thearmature 26 and the right hand pole piece 24. It is further apparentthat af the same time the arrows S6 representing the overall controlfield are in the same direction as the left hand arrows 84 representingthe left hand normalfield. Thus, the overall control field is additivewith respect to the left hand normal field represented by the arrows 84and greatly augments the left hand normal field to cause the armature 26to be attracted with a snap action to the left hand pole piece 20. Inlike manner, energizing the two 4control coils 12 and 13 in the oppositerespect weakens if not cancels out the left hand normal fieldrepresented by the arrows 8d and augments the right hand normal fieldrepresented by the arrows 85 to cause the armature to snap over to theright hand pole piece 24.

When the armature 26 is at its right hand position as viewed in FIG. l,the two wire switch arms 32 and 34 are in the position shown in solidlines in FIG. 5. In FIG. 5 it is apparentthat the conical cam surface 82of the boss 8l) wedges the wire spring arms 32 and 34 snugly against thecorresponding switch contacts 36. FIG. 5a shows how at this time theconical surface 66 of the operating head 35 cooperates with the conicalcam surface 32 of the boss 80. Itis to be noted in FIG. 5a that theswitch arm 32 is not in the bottom of the recess that forms the two camsurfaces 65 and 66 of the operating head 35. The wire switch arm 32 isflexed laterally by the cam surface 66 of the operating head. Thus theoperating head by its cam surface 66 tends to spread the two wire switcharms 32 and 34 apart and in doing so liexes the wire switch arms tocause them to exert pressure against the two lfixed switch contacts 36.In like manner when the armature 26 abuts the left hand pole piece 20,each of the two wire switch arms 32 and 34 is forced by the second camsurface 65 of the operating head 35 into wedging position between thecam surface 78 of the boss 76 and the corresponding fixed contacts 38.

Even without the two bosses 76 and 80, the two wire switch arms 32 and34 would exert pressure against the fixed contacts 36 and 38 by virtueof the two conical surfaces and 66 of the operating head 35 andespeci-ally so because the fixed contacts 36 and 38 and the interveninginsulating washers 74 are adjusted to flex the two wire switch armsagainst the operating head. It is to be noted that the two wire switcharms cannot lie at the bottom of the recess that forms the two camsurfaces 65 and 66 of the operating head 35 unless the two wire switcharms are perpendicular to the taxis of the operating head and thiscondition occurs only momentarily as the two wire switch arms swingbetween their limit positions. At their limit positions the two wireswitch arms are nonperpendicular to the axis of the operating head 35and therefore are out of the bottom of the recess, the two wire switcharms being thus flexed by the operating head for increased contactpressure.

To achieve the desired high operating speed, the mass of the armature 26is relatively small, the range of travel of the armature is relativelyshort and Ithe magnetic iiux is highly concentrated in the region ofarmature travel. In one successful embodiment of the invention thearmature 26 combined with the operating rod 28 and the operating head 35has a total weight of only 1A gram, the travel of the armature betweeni-ts two opposite lim-it positions is only .010 inch and the magneticforce that holds the armature against a pole piece is on the order of300 grams. This holding force is sufficient t-o withstand a force ofover 1200 G along the axis of movement of the armature and the armatureis immune to G forces that are exerted transversely of its axis ofmovement.

Reliability over an extended service period of a high number of cyclesrequires that the two switch arms maintain continuous contact with thefixed contact elements 36 and 38 whenever the switch arms are moved intothe range of the fixed contact elements. If continuous contact is notmaintained, spark erosion will develop and -the galled metal wiil thencause 4the switch arms to jump with consequent interrupting of thecurrent. Plating or alloying the fixed contacts and/ or switch arms witha noble metal is helpful for preventing oxide formation or otherinsulating films, but of equal importance are the described mechanicalprovisions for causing the two resilient wire switch arms to exertwiping pressure against the fixed contacts.

The second embodiment of the invention shown diagrammatically in FIG. 6is largely similar to the first embodiment of the invention 4asindicated by the use of corresponding numerals to indicate correspondingparts. Here again a left hand permanent magnet 16a and a right handpermanent magnet 18a cooperate with two pole pieces 20a and 24a to forma ferromagnetic structure to yieldingly hold an armature 26a to twoopposite lim-it positions. The two magnets are sho-wn separately by aferromagnetic ring which corresponds to the previously mentioned disk14. Inside of the two permanent' magnets 16a and 13a are correspondingcoils 12a and 13a.

The second embodiment of the invention differs from the first in thatthe two permanent magnets y16a and 18a cooperate to form a singletoroidal magnetic field instead of two opposite magnetic fields and thetwo coils 12a and 13a create two opposite toroidal control Ifieldsinstead of a single overalll control field. In FIG. 6a the outer arrows`92 indicate the normal overall magnetic field created by the twopermanent magnets 16a and 18a. gized in one respect they create twoopposite toroidal control fields of flux indicated by the inner arrows94 and -95 respectively. it `will be noted that the right hand controlfield indicated 'by the arrows 95 augments the portion of the normalttield that is created by the right hand permanent magnet 18a while theleft hand control field indicated by vthe arrows A94- diminishes ornullifies the portion of the normal eld that is created by the left handpermanent magnet 16a. Consequently, the armature y26a is shifted fromits left hand position to its right hand position. It is apparent thatif the current ilow through the two coils is reversed the two controlfields are reversed to cause the armature to shift to the right byweakening the portion of the normal field that is created by the left'hand' permanent magnet and augmenting the port-ion of the normal eldthat is created by the right hand permanent magnet. It is apparent that,if desired, the central spacer ring 90 may be omitted with a singlecylindrical electromagnet substituted for the pair of cylindricalelectromagnets.

It is to be noted that in -both of the described embodiments of theinvention, the actuating armature is latched in its two alternate llimitpositions by the magnetic force created by the permanent magnets. Thusno outside power is required for holding the armature.

It Iwill be readily appreciated by lthose skilled in the art that eitherof the two described bistable devices may be employed las -a chopper.Special advantages of such a chopper are minimum noise and absence ofbounce.

IFIG. 7 indicates the manner in which the principles of the inventon maybe incorporated in a -monostable device. In thi-s instance themonos-table device may be Ia relay with the previously described contactarrangement or with any other desired contact arrangement.

The cylindricatl assembly shown in fF-IG. 7, which may be suitablyencased as previously described, includes: the usual central axial tubeof a Suitable smooth plastic such as Teon; a spaced pair of coaxialcoils cornprising a left hand coil 112 and a right hand coil |113 bothsurrounding the tube 110; a central ferromagnetic disk 1114 with acentral aperture to receive the tube When the Atwo control coils 12a and13a are ener- 110; a single right hand cylindrical permanent magnet 116;a spacer sleeve 118 of non-magnetic material such as aluminum or brass;a left hand pole piece 120 having `an axial extension 122 in the tube111i; a right hand pole piece '124 having an axial extension 125 in thetube 110, the two axial extensions of the two pole pieces being spacedapart to form a gap or working space between the two pole pieces; anactuating armature 126 slidingly mounted inthe gap between the two polepieces; and an operating member 128 which extends through an axial bore`130 in the right hand pole piece `124 and which operates a switchingmechanism in the previously described manner.

In the absence of energization of the two coils 112 and 113 the normaltoroidal magnetic field created by the single permanent magnet `116attracts the armature 126 and holds the armature `126 at its normalright hand position as shown in FIG. 7. When the two coils i112 and 113are energized, `the right hand coil i113 Iweakens or cancels the normalmagnetic field created by the permanent magnet l116 yand the left handcoil 112 creates a toroidal magnetic field to attract the armature 126out of lits normal position to Vits left hand limit position. When thecurrent flow through the two coils terminates, the armature 126 snapsback to its normal right hand position.

FIG. 8 shows how the principles of the invention may be applied to theconstruction of a push button switch. The structure shown in FIG. 8 isin large part similar to the construction of the mono-stable device orrelay shown in FIG. 7, as indicated by the use of corresponding numeralsto indicate corresponding parts. It may be seen in FIG. 8 that anactuating armature 126 is mounted in the previously described manner ina ferromagnetic structure that includes the two pole pieces 1211 and124. The operating member 128 that extends through `the bore 131) in thepole piece 1241 functions in the previously described manner to controlat least one switch arm. FIG. 8 shows the operating member 128 carryinga previously described operating head to control two switch arms 32 and34.

The ferromagnetic structure in FIG. 8 is mounted in a. casing comprisinga cylindrical shell 132 and two end walls 134 and 135 in the form ofdiscs. The cylindrical casing provides a compartment 136 for the switchmechanism including the two switch arms 32 and 34. The operating member12S that carries the operating head 35 extends beyond the operating headthrough a bore in the end wall 135 to an exterior push button 138. Thepush button 13S is normally held at an outer position by a concealedcoil spring 140 and is retained by a radially inward flange 142 of thecylindrical shell 132. The flange 142 extends into an outercircumferential groove 144 of the push button, the groove beingsubstantially wider than the thickness of the flange to permit therequired range of axial movement of the push button.

The push button switch shown in FIG. 8 includes the previously describedcoils 112 and 113. When the two coils 112 and 113 are energized, theright hand coil 113 weakens or cancels the normal magnetic field createdby the permanent magnet 116 and the ,left hand coil 112 creates atoroidal magnetic field to attract the armature 126 out of its normalposition to its left hand limit position. When the current flow throughthe two coils terminates, the armature 126 is snapped back to its normalright hand position by the magnetic field of the permanent magnet 116.The push button 138 may be manually depressed as an alternate means forshifting the armature 126 out of its normal position to its left handposition.

In FIG. 9 illustrating the application of the invention to theconstruction of a dual push button switch the construction is largelysimilar to the previously described construction shown in FIG. l, asindicated by the use of corresponding numerals to indicate correspondingparts. The structure mounted in the cylindrical housing 52a differs inonly two respects from the structure mounted in the cylindrical housing52 in FIG. l. One difference is that the axial extension 22 of the lefthand pole piece 20 is provided with an axial bore 145 to receive in asliding manner an operating member 146 which is of the same character asthe operating member 28 in FIG. l. The second difference is that theoperating member 146 which carries the operating head 35 extends at bothof its ends through bores in the two headers 48 with substantial endportions of the operating member exposed outside the two ends of thecylindrical housing.

The cylindrical housing 52a is adapted by suitable means (not shown) forsupport adjacent a panel 148 which has two spaced apertures 150 to cleartwo push buttons 152 and 154. The two push buttons are mounted on theopposite ends respectively of a yoke 155 that has two arms 156 and 158overhanging the opposite ends of the operating member 146. The yoke 155is pivotally mounted on a bracket 159 on the cylindrical housing 52a andis normally held at an intermediate or neutral position by the two armsof a leaf spring 160.

In the previously described manner, the two coils 12 and 13 may beenergized selectively by remote control to cause the armature 26 toshift to its two alternate positions selectively but the armature 26 mayalso be shifted by manual operation of the two push buttons. With theparts positioned as shown in FIG. 9, depression of the switch button 154rocks the yoke 155 to cause the yoke arm 153 to shift the operatingmember 146 to the left, thereby to shift the armature 26 from its'righthand limit position to its left hand limit position. Subsequently theswitch button 152 may be depressed to shift the armature 26 back to itsright hand position. Thus, two switch arms 32 and 34 associated with theoperating head 35 may be actuated either by remote controlv or by manualpush button control.

If desired, the coils 112 and 113 may be omitted from the push buttonstructure shown in FIG. 8 and the coils 12 and 13 may be omitted fromthe push button structure shown in FIG. 9. Thus both of theseembodiments of the invention may beadapted to serve as simple manualcontrols only.

My description in specific detail of the selected practices of theinvention will suggest various changes, substitutions and otherdepartures from my disclosure without departing from the spirit andscope of the appended claims. l

I claim:

1. In an actuator of the character described, the combination of:

ferromagnetic means including two opposite pole pieces havingconfronting spaced axially aligned portions forming a working gap;

an armature to serve as an actuator, said armature being mounted in saidgap for movement between two alternate limit positions against said twopole .pieces respectively;

two coils surrounding said portions of the two pole pieces respectively;and

two cylindrical permanent magnets surrounding said two coilsrespectively, to create two opposed magnetic fields to cause saidarmature to be held magnetically against whichever pole piece it may bepositioned, said two coils being cooperative to form a singlecontrolling magnetic field, said two coils being adapted forenergization in opposite respects selectively to shift said armatureacross said gap against the two pole pieces selectively, said twopermanent magnets carrying the outermost flux paths in the operation ofthe device.

2. In an actuator of the character described, the combination of:

ferromagnetic means including two opposite pole pieces havingconfronting spaced axially aligned portions forming a working gap;

an armature to serve as an actuator, said armature being mounted in saidgap for movement between two alternate limit positions against said twopole pieces respectively; l

two coils surrounding said portions of the two pole pieces respectively;and

two cylindrical permanent magnets surrounding said two coilsrespectively to hold said armature against whichever pole piece it maybe placed, said permanent magnets being of the same polarity to create asingle magnetic field, said two coils being opposed for energization intwo respects selectively to shift said armature across the gap to thetwo pole pieces selectively.

3. In an actuator of the character described, the combination of:

ferromagnetic means including two opposite pole pieces havingconfronting spaced axially aligned portions forming a working gap;

an armature to serve as an actuator, said armature `being mounted insaid gap for movement between two alternate limit positions against saidtwo pole pieces respectively;

two coils surrounding said two portions of the two pole piecesrespectively; and

a cylindrical permanent magnet surrounding one of said coils to -createa normal magnetic field for normally holding said armature against thecorresponding pole piece, said two coils being opposed for energizationin one respect to cause the coil surrounded by the permanent magnet too-ppose said magnetic field to reduce the attraction of saidcorresponding pole piece for the armature land to create a secondmagnetic field associated with the other pole piece to attract thearmature to the other pole piece.

4. In a device of the character described, the combination of:

an armature reciprocative between two alternate limit po-sitions;

ferromagnetic means including two spaced confronting pole pieces forminga working gap;

permanent magnet means magnetically linked with at least one of said twopole pieces to yieldingly hold the armature against said one pole piece;

electromagnetic means to shift the armature across the working gap;

an operating member mechanically connected to said armature to movebetween two corresponding limit positions, said operating members havinga peripheral recess with one side of the recess forming a cam surface;

a fixed contact;

a swingable switch arm cooperative with said contact to open and close acircuit, said switch arm extending into said recess for movement of theswitch arm by the operating member between two corresponding limitpositions, said contact being on the side of the switch arm oppositefrom the operating member and said cam surface of the operating mem-Iber being positioned to cam the switch arm against said contact at oneof the two limit positions of the switch arm.

5. A combination as set forth in claim 4 which includes means providinga fixed guide surface in convergent relation to said contact and in thepath o-f the movement of the switch arm for additionally camming theswitch arm against the contact.

6. In a device of the character described, the com bination of:

an armature reciprocative between two alternate limit positions;ferromagnetic means including two spaced confronting pole pieces forminga workin-g gap; permanent magnet means magnetically linked with at leastone of said two pole pieces to yieldingly hold the armature against saidone pole piece;

electromagnetic means to shift the armature across the working gap;

an operating member mechanically connected to said armature to movebetween two corresponding limit positions;

a fixed contact;

a swingable switch arm cooperative with said contact to open and close acircuit, said switch arm being operatively connected to said operatingmember for movement of the switch arm by the operating member betweentwo c-orresponding limit positions, one of said limit positions `of theswitch arm being at said fixed contact; and

means providing a fixed guide surface in convergent relation to saidfixed contact and in the path of movement of the switch arm for cammingthe switch arm' against the contact.

7. In a device of the character described, the `combination of:

anarmature reciprocative between two alternate limit positions;

ferromagnetic means including two spaced confronting pole pieces forminga working gap;

permanent magnet means magnetically linked with at least one of said twopole pieces to yieldingly hold the armature against said one pole piece;

electromagnetic means to shift the armature across the working gap;

an operating means mechanically connected to said armature to movebetween two corresponding positions, saidoperating means having a pairof opposite surfaces;

a pair of swingable resilient switch arms loperatively connected to saidoperating means for movement thereby to corresponding limit positions;and

fixed 'guide struct-ure having a pair of guide surfaces :for said switcharms, said guide structure including yfixed contacts for cooperationwith the switch arms `at limit positions of the switch arms, said pairlof guide surfaces straddling the pair of switch arms and the switcharms straddling the pair of opposite surfaces of the operating means, atleast one of the two lpair of surfaces being inclined for fiexure of theswitch arms into pressure contact with the guide structure.

8. A combination as set forth in claim 7 in which said operating meanshas recesses on its opposite sides receiving the switch arms foroperation thereof, said recesses being tapered for cam action againstthe switch arms at limit positions of the switch arms.

9. A combination as set forth in claim -in which the pair o-f guidesurfaces of .the guide structure are also inclined to cam the switcharms against the contacts as the switch arms approach the contacts.

l10. In an actuator of the character described, the combination of:

an armature to serve as actuator means, said armature beingreciprocative between two limit positions; magnetic means having twoconfronting poles at the two limit positions respectively of thearmature to yieldingly hold the armature at whichever of the two limitpositions it may occupy;

electromagnetic control means to create two opposite controllingmagnetic fields :selectively to selectively cooperate with the permanentmagnetic fields to shift the armature to its two limit positionsselectively;

a switch arm operatively connected to said operating means for movementthereby to corresponding limit ipositions;

a fixed contact for cooperation with said switch arm at a limit positionthereof; `and a fixed cam adjacent said fixed contact to cam the .switchsaid ferromagnetic structure enclosing the two coilsand a portion of theferromagnetic structure extending radially inwardly between the twocoils to said gap; and two cylindrical permanent magnets in saidferromag netic structure surrounding the two coils respectively to holdsaid armature against whichever pole it may be placed,

said two coils being adapted for energization in opposite respectsselectively to shift said armature Iacross said gap to its two limit`positions selectively,

said two :permanent magnets enclosing the outermost paths of magneticllux of the device, said two pole pieces extending axially a substantialdistance inward into the interiors of the corresponding coils to reducethe axial dimension of said gap,

said armature being` correspondingly reduced in axial dimension toreduce the mass of the armature and thereby reduce the inertia of thearmature to permit the armature to shift between its alternate limitpositions in a time interval of less than IAOOO of a second.

12. A combination as set forth in claim .11 in which said two permanentmagnets are of opposed polarity and in which said two coils arecooperative in their effect on the armature.

13. A combination as set forth in claim 11 in which said two permanentmagnets are of the same polarity to create a single magnetic -eld and inwhich said two coils are opposed.

14. A combination as set forth in claim 11 which includes manual meansto shift said armature from one `of said pole pieces to the other.

15. A ycombination as set forth in claim 14 in which said manual meanscomprises a .push button operatively connected to said armature to shiftthe armature from one limit position to the other in opposition to theholding magnetic uX.

`16. A combination as set forth in claim 14 in which said manual meanscomprises two tpush buttons operative to shift said armature in itsopposite directions respectively.

17. A combination as set forth in claim 11 which includes:

a 4plastic .sleeve enclosing said gap, said sleeve slidingly embracingsaid arma-ture to guide the armature with low frictional resistance.

References Cited by the Examiner UNITED STATES PATENTS 1,572,708 2/ 1926Eaton 200-87 2,505,904 5/1950 Matthias et al 317-172 2,591,336 4/1952Bordelon 200-87 2,769,103 10/ 1956 Kristiansen 317-172 2,919,324 12/1959 Schuessler 200-93 3,017,476 1/ 1962 Becka 200-153 3,022,450 2/196'2Chase 317-171 3,030,469 4/1962 -Lazich 317-171 X 3,040,217 6/1962 Conrad317-172 3,070,730 12./1962 Gray et al 317-171 3,105,925 10/1963 Musgrave317-171 3,119,940 1/1964 Pettit et al 317-171 X BERNARD A. GILHEANY,Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

1. IN AN ACTUATOR OF THE CHARACTER DESCRIBED, THE COMBINATION OF:FERROMAGNETIC MEANS INCLUDING TWO OPPOSITE POLE PIECES HAVINGCONFRONTING SPACED AXIALLY ALIGNED PORTIONS FORMING A WORKING GAP; ANARMATURE TO SERVE AS AN ACTUATOR, SAID ARMATURE BEING MOUNTED IN SAIDGAP FOR MOVEMENT BETWEEN TWO ALTERNATE LIMIT POSITIONS AGAINST SAID TWOPOLE PIECES RESPECTIVELY; TWO COILS SURROUNDING SAID PORTIONS OF THE TWOPOLE PIECES RESPECTIVELY; AND TWO CYLINDRICAL PERMANENT MAGNETSSURROUNDING SAID TWO COILS RESPECTIVELY, TO CREATE TWO OPPOSED MAGNETICFIELDS TO CAUSE SAID ARMATURE TO BE HELD MAGNETICALLY AGAINST WHICHEVERPOLE PIECE IT MAY BE POSITIONED, SAID TWO COILS BEING COOPERATIVE TOFORM